0191-9067/85 $3.00 + .00 Copyright ® 1985 SUNSAT Energy Council ELECTRIC PROPULSION TEST ONBOARD THE SPACE STATION YOSHIHIRO NAKAMURA National Aerospace Laboratory 1880 Jindaiji-machi, Chofu Tokyo 182, Japan KYOICHI KURIKI Institute of Space and Astronautical Science 4-6-1 Komaba, Meguro-ku Tokyo 153, Japan Abstract — The electric propulsion system of high specific impulse will be necessarily one of the most useful cargo orbit transfer vehicles in future expanding space activities. Testings of high power electric propulsion systems (MPD and ion thrusters) onboard the Space Station and/or a free flyer (Bus Platform) away from the station are planned to demonstrate the feasibilities of the propulsion systems and to observe the interference of thruster plasma exhaust with the spacecraft and the ionospheric environment. It is of great advantage in reliability as well as cost, to conduct long-term tests of such thrusters in space that exhaust significant rate of ionized and non-condensable propellant. Several flight modes of the Platform in the proximity of. and in the long distance from, the Space Station are described to verify the produced thrusts and to monitor the plasma plume in the geomagnetic field. INTRODUCTION Large scale Solar Electric Propulsion will play an important role in the coming space station era, and its development should be promoted. The space transportation to and from the space station will be active, and the propellant consumption for it increases very much. The utilization of the Solar Electric Propulsion System (SEPS) can save launch costs significantly due to the reduction of propellant consumption by one order. In the construction of Space Power Station, for example, a great deal of materials and large structures assembled on the space station in a lower orbit must be carried to the geosynchronous orbit by the propulsion systems with the thrusters of low thrust and high specific impulse. The large structure usually has a gigantic solar array which can supply abundant electric power. The SEPS is a most promising candidate for a Cargo Orbit Transfer Vehicle. It has a long life and is used as a space tug several times only by supplying propellant at the Space Station. Before the application of the SEPS to practical use, it should experience operational testing long enough to demonstrate its durability. It is more economical and advantageous to conduct such a long test on the space station than on the ground. Furthermore, the motion of the spacecraft thrusted by the SEPS and the behavior of its plasma exhaust in the geomagnetic field are very interesting in practical use and physical meanings. In the present paper, the outline of the SEPS test plan proposed as APT (Advanced Propulsion Test) on the space station is described (1,2).
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